1993: Endeavour's critical Hubble repair mission

The first Hubble servicing mission, carried out by Endeavour, involved a record five spacewalks, two of which lasted more than seven hours.

The second and fourth spacewalks of the mission were carried out by Tom Akers and Kathy Thornton, who replaced some of the telescope's solar panels and - most critically - installed equipment to correct an error with Hubble's main mirror.